Hi thanks Keith, it is M42 mount and came with some other lenses. I red about the Sigma making also, although there are other Accuras which seem to point to other lensmakers.
As with many of those lenses, like Soligor's for example, it is very hard to find out in which factory a certain lens was made.
I was testing this one with some other 28mm lenses, which I bought cheaply, together with a Chinon 28/2.8 which looked impressive, but is worthless for wide open bokeh. No sharpness at all.
Liked the Accura even more then the Vivitar 28/2 that day.
Here is a sample from the Vivitar on that same cloudy day.
(Now I look at it, it's not so bad
)
BTW we were almost posting simultanious, your Sima lens is great for suspicious photography.
Michiel